Astronomers have yet to discover a single world just like our own — an Earth-sized planet orbiting a Sun-like star at the right distance for liquid water. But there may be a shortcut for finding star systems that host such planets: look at the chemistry of the star.

Astronomers from McDonald Observatory and elsewhere developed that tip after spending several years studying a star that’s the best “twin” to the Sun yet seen — pretty much all of its specs are within a percent or so of the Sun’s.

HIP 56948 is about 200 light-years away. It’s between the Big Dipper and the Pole Star, Polaris, although it’s too faint to see without a telescope.

Stars in the prime of life are made mainly of hydrogen and helium, the two lightest elements. But they also have a smattering of heavier elements. The percentages are tiny, but there’s a good variation from star to star.

Using telescopes in Texas and Hawaii, astronomers found that the traces of heavier elements in HIP 56948 almost exactly match those found in the Sun.

That could be a result of the process that gives birth to planets and asteroids. If so, then HIP 56948 might have a system of planets similar to our own.

So far, the search for planets there has turned up empty. But the searches haven’t had enough time to find an Earth-like world. If they do find one, though, it could pave the way for finding many others — just look for stars whose chemistry matches the Sun’s.